The present invention relates generally to protective hoods and neck seals for use in protective hoods and, more particularly, to protective hoods and neck seals for use therein in which a multi-component neck seal is heat sealed to the head covering or hood portion of the protective hood.
There is an ever-increasing threat of release of chemical and biological warfare agents into public locations such as office buildings and subway systems. As a result of this trend, it has become increasingly important to provide the occupants of these spaces with emergency protective devices for such agents. In that regard, even brief inhalation and exposure of the eyes to airborne toxic chemical and biological agents (associated, for example with terrorist activity) pose a serious threat to unprotected individuals. For example, agents such as Sarin are lethal in dosages as low as of 100 mg/m3-minute.
While it is well known to use gas masks for protection against chemical and biological warfare agents, hoods typically have not been used for that purpose. However, a number of protective hoods are asserted to provide effective respiratory and eye protection against toxic substances present in environments including smoke and fire. One such device is described in U.S. Pat. No. 5,226,409. That device is purportedly suitable for protection against toxic fumes and includes a four-layer laminated head covering. The head covering is tubular in configuration with a closed top, and a bottom end having a neck seal with an opening to permit the entry of the user into the hood. The neck seal includes a flat elastomeric (for example, natural rubber or silicone rubber) annular ring having a circular opening in its center and a central flange extending upwards from the opening perpendicular to the surface of the ring. At the periphery, a circumferential flange extends downward and generally perpendicular to the surface of the annular ring and is bonded to the sidewall of the head covering. It is practically impossible, however, to heat-seal a crosslinked elastomer to a thermoplastic.
U.S. Pat. No. 5,146,636 describes a heat and smoke protective hood including a bag-like head covering fabricated from a heat resistant, gas-impermeable sheet material (that is, polyimide) adapted to fit loosely over the head of the wearer. The protective hood also includes a filter (activated carbon cloth) provided in an aperture of the hood covering to remove toxic substances and harmful ingredients from air inspired by the wearer. A flame retardant annular skirt (fabricated from, for example, an aromatic amide) is attached to the circumference of the head covering, and an elastic neck seal portion (for example, latex or Neoprene latex sheet) is attached to the opening of the head covering.
U.S. Pat. No. 4,683,880 discloses a protective head covering including a transparent, tubular portion fabricated from KAPTON available from DuPont (a polyimide film). The protective covering has a closed upper end and a lower skirt portion adapted to fit over at least the head of the user. A resilient, annular neck seal (for example., silicone sheeting) is adhesively bonded to the interior of the tubular head covering.
U.S. Pat. No. 5,113,854 discloses a protective hood assembly for respiratory protection from smoke and noxious gases. The assembly includes a clear Teflon film hood having a scrubber canister and an exhaust valve. A neck seal is connected to the lower marginal edge of the hood. A spring-like hoop is also connected to the lower marginal edge of the hood. A bib is carried by the spring-like hoop and supports an oxygen generator. A neck seal carried by the lower marginal portion of the hood engages the neck of the user when the hood is donned over the head of the user.
Certain of the materials used in currently available protective hoods are generally unsuitable to protect against chemical and biological warfare agents. Moreover, the neck seal portions of currently available protective hood devices are inadequately attached to the head covering of the protective hoods. In that regard, not only must the neck seal be impermeable to toxic agents and sufficiently elastic to accommodate a wide range of head sizes, it must also securely attach to the hood covering. In many current protective hoods as, for example, described above, adhesive bonding is used to attach the neck seal directly to the hood. In such an attachment, however, it is very difficult to maintain an adequate adhesive chemical bond between the head covering material (for example, a polyimide or a fluoropolymer) and an elastic neck seal material. Over time, the strength of the adhesive bond to the head covering material decreases thereby permitting toxic agents to enter into the hood. This phenomenon is accelerated if the hood is stored at elevated temperatures (for example, in excess of 105° F.).
It is, therefore, desirable to develop protective hoods that substantially reduce or eliminate the above problems.